Are the smoke associated with the person like a signature or the color symbolizes something else?
Waaaaaaay back in S1 and early S2, someone sat down and wrote out every instance of Smoke on ONCE and who was associated with it and what was going on when it happened. So far as I can tell, Regina almost always uses PURPLE and Zelena almost always uses GREEN (the latter seems to be a nice call back to OZ and that myth); Rumple uses red, especially if he vanishes. Pan’s smoke was Green but when Regina cast her curse in S1 it was black. I’m not sure they are specifically associated with one person anymore.
With Regina, only the Evil Queen used black and Regina per se used purple. I think it have to do with the intention now that I think it through. I think each color means a certain emotion or motivation. Green it’s fair to say it’s associated with wickedness as Rumple reappear to Zelena after he fooled her and when Peter Pan recast the Dark Curse, that’s a theory.