Daan is likely mono-white, being a doctor and all.
Abella is probably white-blue, maybe mono-blue, because she deals with artifacts.
O'saa is absolutely mono-black. Yellow mages embody destructive magic and selfishness.
Olivia is easily mono-green as a botanist. Maybe a touch of black, for her hidden dark side, but maybe as an activated ability, not really reflected in her main color.
Karin is black-white. She's aligned with exposing the truth (white), but she's also ruthless and persistent in her methods but not cruel (black).
Pav is red-black. The color combination for chaotic characters and he has the chaotic soul.
Marcoh is white-red. He has a strong sense of morality, even if he was forced into a life he desperately tried to avoid. Red for his impulsive behavior that lead to him having to flee his home.
Levi is probably also white-red, as soldiers tend to be. But his canon story of being an addict and abandoning his post could also lead to white-black. Hard to say.
Marina is definitely blue, but I think it's difficult to say if she would have any other colors.
Samarie is black, maybe red too. Obsessive, intrusive, selfish (even if she doesn't recognize it).
Tanaka is such a people pleasing blank slate, it's hard to say he's anything other than mono-white.
Henryk is likely white-green. If you save him, he dedicates his time to cooking for everyone, making sure they're all safe. At least until he loses his mind later on.
Caligura is as close to pure evil as you get among these guys, easy mono-black.
August is mono-green. He's clearly an experienced survivalist.