You mean one of the greatest design decisions of all time?????
It's almost like they're implying certain things about the characters (or well, Griffin at least since he was always wearing that same outfit but she made some changes to her wardrobe) if you believe this shared color palette was intentional. Which... how are you going to invent almost the exact same color palette accidentally and for the same show, for characters who not only interact, but used to be partners? This does not sound like a coincidence at all. So then we're left with the question of what was going through Griffin's head when she switched to his color scheme after the final battle on Domino.
Her first outfit from when she actually worked with Valtor is purple but it is a completely different shade from his purple and there's no red in sight. In fact, her hair color is closest to any of the colors he wears, particularly the shade of his pants and vest.
Later in her battle outfit from SotLK the purple is almost completely gone, replaced by a light blue that turns into very light purple that's barely present in her outfit during the show. Seems like she was trying to escape from her association with Valtor. Except for the cape that is starting to suspiciously remind of Valtor's coat as it is mere shades away from being the exact same color.
MA'AM?????? Did you steal his clothes????????? Is this some elaborate ritual of mourning - making yourself a living, walking shrine of this man you betrayed?!?!?!?!?!?! It's almost like she said "I cannot bear the thought of there not being any part of Valtor left in the world. Guess I'll start dressing in his colors to literally wear the memory of him and that would be the way the entire world sees me, forever."
Oh, they were insane for this!
P.S. My headcanon is that she started wearing gloves because she hates the mark she's left on the world. Sort of like a subconscious impulse to stop leaving her fingerprints over everything she touches because she's done enough harm. And the gloves are light purple aka the only color that she wears that isn't also part of his color scheme. So it's like she realizes the negative impact their relationship had on all the rest of her interactions with the world which is why she's trying to distance herself from that in order to stop making the universe a worse place. But not only is her color scheme his color scheme but he also wears gloves so that's just another similarity (if only on the surface).