It was my understanding that Mosquitos were low altitude bombers and attack aircraft so in that role they’ll need to be camouflaged to make sighting from above more difficult.
So use ground colors.
Grey is pretty much a universal “blend” color as even a fully grey or dull silver aircraft is very difficult to spot.
Silver was the worst color that Cirrus could have used.
Wasn’t the photo reconnaissance version of the Spitfire all grey?