Rise from the Grave doesn’t overwrite any previous colors or types. Rather, it adds another color and another subtype.
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
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.
Put target creature card from a graveyard onto the battlefield under your control. That creature is a black Zombie in addition to its other colors and types.
