Yes, as it is in French, some colors have no gender: verde, marrom, laranja, rosa, cinza, lilás,...
In addition to that, some colours have no plural neither: camisas cinza, camisas rosa, camisas laranja
Just a note: Only verbs can "conjugate" (have a conjugarion); nouns and adjectives "decline" (have a declension).
Why is sao and not somos used here? As the conjugation for nos is somos I am just a little confused. Thanks for any help!
Cuz são and somos don't mean the same like in English. And there are two shirts, so it's like to say they are= elas são. The word somos it's used we your talking about me and you(we), for example we are friends= nós somos amigos. The verb change when it's used with different pronouns.