Because of the way the menus are set up you can edit everything else (including traits and homeworld) after selecting a civ, but you can only select premade color pallettes/ship styles unless you create a copy of that civ, and then you get a different menu with a different layout. Basically you have to create what the game considers separate civilization just to have a custom color scheme.
Basically what I'm asking for is the flexibility from galciv 2
