Nyssus coloripes

Nyssus coloripes
Spotted Ground Swift Spider
Notes from Raven (2015) pp.133-135
highly variable and forms a complex of closely related "species".
occurs widely in Australia
diurnally active (i.e. daytime) on the ground in open forest or in open spaces near closed forest.
Defining combination of characteristics:
• the distal half of femur through to the tarsus of leg I (often also leg II) is yellow, all other legs are dark brown or black.

But in this photo the tarsus of leg 1 is not yellow - does this matter?

Good question! To an extent, yes, the colour does matter, however, it is a comparatively minor ID feature. The World Spider Catalog currently lists 14 species of the genus Nyssus from Australia, of which only two species are known to be distributed in ACT/NSW: N. albopunctatus & N. coloripes. The biggest, most distinctive differentiation between the two would be the abdomen pattern where N. coloripes has the pattern of white (often also yellow - described for females on the species page) shapes/spots - as seen in your sighting - while N. albopunctatus has two mostly symmetrical lines of white patches/spots. The legs and carapace would follow closely behind providing clarity on which species it is. The legs of N. coloripes has some colour difference towards the tips of the the legs, most notably on the first and second while N. albopunctatus doesn't. The carapace of N. coloripes generally has a single solid medial strip of white, whereas N. albopunctatus would have a solid medial strip of white which then branches off into two or three angled and short lines just above the abdomen.
The abdomen of your sighting is definitely that of N. coloripes: looking purely from the top, there is one dot, then two, then one (shaped like a "chevron" as described in Raven's work), then two more closely situated spots which seems to have merged on your individual. You could look at it the other way and compare it with N. albopunctatus which should have two neat rows of spots running along the abdomen.
The medial white line on the carapace (i.e. head) is solid and doesn't branch at the base, suggesting N. coloripes once more.
As for the leg colour, your sighting would be a clear example of variation between individuals in the tone, depth and shade. I would describe the colour of leg 1 in your sighting to be more of a dull and faded red/orange-brown than other sightings which have clear shades of bright yellow or orange, but this level of variation is definitely possible within Nyssus coloripes and could be due to location, habitat, age etc. The descriptions I provided on the species page is from a single taxonomical paper and encompasses the characteristics that are typically found on this species wherein a particular individual may not perfectly fit every description. So yes it does matter but it isn't strictly consistent with every individual and the alignment of this one with the majority of the remaining features solidifies indication that the ID of this is N. coloripes.
I would also like to note that the information I put into the species page isn't the only resource with references and data on the species so it might help to have some visual comparisons too. I chose to put in notes from Raven's paper as it isn't easily accessible and has information beyond what is needed here. If you would like to look further for visual resources, I would recommend either looking through sightings on citizen science platforms like NatureMap, ALA and iNaturalist, or other informative sites like findaspider.org or arachne.org.au. The following has some information and an example of N. coloripes with colour variation: http://www.arachne.org.au/01_cms/details.asp?ID=1807
I hope this is makes sense and is agreeable to some extent. Feel free to ask more questions and all the best for your future exploration of spiders and beyond! :)