It doesn't describe a physical manifestation, so I would default to there being none. A physical manifestation has more drawbacks than benefits, such as RP interactions and tipping your hand, so unless some FAQ clarifies it or some other rule says so it doesn't have a tell.
I’d use the Iconic Shifter’s artwork as an example of what a minor aspect would look like - her hand have turned partly into bird talons and her hair seems to have turned into feathers.
I also don’t think there are too many social problems with it like WatersLethe was suggesting - manifesting it works similarly to a barbarian’s rage so you’ll only be doing it in combat anyway. So to go back to the Iconic Shifter, how she looks in the artwork is her in combat, it’s like seeing Amiri mid-rage or Lem mid-performance. When not fighting, I expect that she looks entirely human.
Ah. This is what I get for answering after having just read the class through once. Forgot that the claws were a separate mechanic to the aspect.
But the basic idea of what I said should still hold - the Shifter Claws ability mentions extending them as a swift action. And in Zova's case, I'd actually think that that would be her transforming her hands into those talons (what with bird claws not being naturally retractable, her talons only having four 'fingers' and so-on).