One of several new titles taken by Saruman during the time leading up to the War of the Ring, and one he apparently took seriously enough to create for himself a strange shimmering and multi-coloured robe. He had previously been Saruman the White, a persona that he explicitly and mockingly abandoned in favour of his new identity as Saruman of Many Colours.

It's not evident why this change from White to Many Colours was significant to Saruman, beyond a clear rejection of his former role as emissary of the Valar in favour of one of personal might. It may be that he was attempting to claim the roles and powers of all the Wizards, and perhaps more besides, but since the meanings of their various colours are never directly explained, it is difficult to speculate on the point.