2018-07-13 : A later effect that changes the affected creature’s colors will overwrite that part of Rise from the Grave’s effect; the creature will be only the new color. The same is true about an effect that changes the affected creature’s types or subtypes.

2018-07-13 : If the creature is normally colorless, it will simply become black. It can’t be both black and colorless.

2018-07-13 : Rise from the Grave doesn’t overwrite any previous colors or types. Rather, it adds another color and another subtype.