Malta colours have many possibilities; in 1936/7, they devised their own colours, for certain areas, comprising an off-white, which matched Malta's stone, a red-brown to match the earth, and a dark blue to match the surrounding sea. Samples were sent to the U.K., and are still available, to view, in the National Archives.
On the first Wasp delivery, consensus is that they used a carrier colour (Wasp would have had a blue-grey Stain 21, for the wooden decks, but more likely is the blue - Deck Blue 20-B - used for the superstructure.)
Before Wasp's second delivery, Malta asked for any further deliveries to be in "Sea camouflage," which should be Dark Slate Grey/Extra Dark Sea Grey, probably over Azure Blue, rather than Sky, since Malta had preferred not to use it; orders, for the aircraft to be painted like that were issued before Wasp left on her second trip.
Edgar