Orange is a relatively much younger word than red (Middle English versus Old English with direct lineage from "Low" German/Proto-Germanic/…/Proto-Indo-European), deriving from the fruit (rather than some may assume the other way around). Orange entered the English language from French royalty (who could afford imported oranges), so arguably Orange is the more historically pretentious color word.

https://en.wikipedia.org/wiki/Orange_(word)

If this were a "lost cat" poster, I'd agree, but for an explanation on cat color genetics, I think the correct term is appropriate.

We call people with orange hair "redheads" so, I don't think this is that different