So far, my characters have a more or less set attire (aside from their "adventuring gear", which they generally only wear between jobs).
But I'm probably going to update their outfits after the current chapter, and then they may have some variation of clothing that will change from time to time, but still within a certain overall design or pattern.
And they do have defined palettes.
Hilda's is yellow, dark yellow, grey, and light red
Olwyn's is mostly green with some brown and rust-red
Ivan's is black, blue, and brown (though not as rich a shade of brown as Olwyn's)
Gunther's is red, grey, black, and tan.
Their palettes may change a little later on, but it will stay somewhat consistent to their original design.