What determines the color of a Force-User's Force Lightning? (Canon or Legends)

We’ve seen multiple occasions of Force Users using Force-Lightning of different colors but never is it explained anywhere what causes those colors for those people. Examples below.

Darth Sidious – Violet/Indigo/Purple

Darth Tenebrous/Darth Maul – Red

Plo Koon – Yellow

Luke Skywalker – Green

Jaina Solo – Black