Essex wore a Measure 21 scheme when she was commissioned, until her refit in San Francisco in April 1944.
This means...in laymen's terms, that the entire ship is painted overall 5-N Navy Blue. The flight deck is painted Norfolk 250 Stain, and the other horizontal surfaces are 20-B Deck Blue.
Testors makes an acrylic of all these colors, in their ModelMaster line.
Regards,
Jeff Herne
Modelwarships.com