"I have orange socks."
Translation:J'ai des chaussettes orange.
French colour adjectives derived from nouns, such as animals, flowers, fruits, gems, and metals, are usually invariable, This mean they only have one gender and are not expressed as plurals.
Though you can certainly have de multiples oranges (multiple oranges), the adjective form of the word never changes, even in the plural:
J'ai acheté des chaussures orange.
"I bought orange shoes."
There is a good reference here: