You can paint it with water based paints BUT the extra weight and drag will affect the performace of a small electric, thats why GWS sells them in diferent coloured foams.

Cub's come in a zillion colour schemes why not look on the net for one with the same base colour and just add the details like roundals (British, Canadian, Aussie), tri colour (France, Spain, DDR) etc, etc even the USA is boud to have white ones (your is white?) with stars and bars