My initial thought is actually, why? It's not like you can really see the lever or the bit of color when the gun is in the ready or firing position. 1911 shooters have gotten by for almost a century without colors on their guns. The safety lever should be used tactilely rather than visually.
Red generally means "fire," so I am not sure I'd use that to indicate "safe." I suppose you could use a dot of model paint if you really must add colors to the pistol.