The arity-1 version was removed because it didn't work for cljs: it relied on a color being encoded in an integer and that wasn't supported in processing.js so I decided to remove to make clj and cljs versions of Quil consistent. Well, actually you can still use arity-1 version to provide full color, but instead of an integer - pass a vector of [r g b] values:
https://github.com/quil/quil/blob/master/src/cljc/quil/core.cljc#L1700 This is not reflected in docs/examples unfortunately, which was an oversight on my part.