Actually, shadows is wrong.Yes, you might get certain temporary tints in the aura associated with mood changes, but in general everyone has anywhere from one to three colors in their aura that are constant and never change. All it takes is a cursory Google search to find that out.
That aside, do I think that associating aura colors with planets and signs is stupid? Not really.In metaphysical circles they assign metals to planets and signs; gold is assigned to the sun, so on and so forth. I've also seen music notes,colors and numbers tied into everything too, in so many words, all things are connected.
So when you take that into account it's really not that far-fetched to think you might see someone's primary, fundamental aura colors, reflected in their natal chart.
For example, my chart has a strong Uranian/Aquarian bent to it, and I've been told I have a LOT of electric blue and white in my aura, along with violet and gold. The gold makes sense if you think of the sun, and I do have a lot of Leo in my chart too.
So absolutely, I think you could see someone's aura colors, reflected in their natal chart. People with predominately earth-element charts probably have a lot more muted, earth-tones in their aura, that kind of thing.
Slightly off-topic a wee bit, but I've wondered about aura colors in connection to the colors associated with the chakras too, and if the colors predominate in someone's aura can tell you where they are in terms of their spiritual evolution. To some extent some websites I read a while ago back me up on this, when they warned that people should check the aura of anyone they're going to go to for spiritual teachings/guidance, and stay far away from those who lacked certain colors - the colors that are associated with the higher chakras.