No he's not. He's definitely grey in the animation, and the majority of G1 Starscream-based toys are also grey. The only times he's been white are the Hasbro/USA Edition MP-3 and the Universe release of the Classics mold. Unless you're biased towards the Marvel Comics depictions of him, in which case that's a limitation of the 3-colour printing of the era. His light grey colour couldn't be reproduced there.