Dashboard – how to change interface colors?

This is a frivolous question, but it’s bugging me that I can’t figure it out myself. Where can I change the WP Dashboard/interface colors?

We’re given a screen with layout choices when we update WP, but what if I get bored with the colors and want to change them? For the life of me I can’t see where to do this and I’ve clicked around EVERYWHERE. Tired of blue and grey!

??

Thanks!