If multiple colors are used, yes. And in AE, "colorfully tiled" is correct (no hyphen between the words); we don't use a hyphen after an adverb that ends in "-ly" preceding an adjective.There is a swimming pool whose bottom and walls are covered with colored tiles. Can I describe it as a "colorfully tiled swimming pool"?
You wouldn't be wrong in BrE, Veli. When an adverb+adjective makes a compound adjective, the use of a hyphen is generally accepted (though not obligatory) if the adjective is attributive, but not if it's predicative. See this BBC article. The tendency these days is not to use the hyphen, because it's usually unnecessary, but I've never seen a BrE source that says it's actually wrong.I would hyphenate that to "*colo(u)rfully-tiled".
*And I would be wrong about that. Thank you Parla.
Below is a pool with vividly blue tiles. Despite that, in my opinion I wouldn't call it "colorful" because it's essentially all one color. To me, "colorful" implies many different colors.Why? If the tiles are colourful (= full of colour = brightly coloured) I see no reason not to say that it's a "colo(u)rfully-tiled swimming pool".