It's all about attracting a mate. I read an article (I wish I had a link) that said that nail polish came around because it covered miscoloration that could be seen as a health problem and therefore make them an ineligible potential mate. The same thing with lipstick. The redder it was, the more men it attracted.
Now it's society that has decided that women would be the attractors, but getting the best potential mate and passing on genes is a biological need.
I'm sure that was clear as mud. It also doesn't really apply in the trans community, but that is the origin of girly colors and clothing.