You can spray paint directly onto eva foam, but there is a good chance it will chip/peel away a more easily. Always be sure to test with a scrap piece of foam before hand though, as certain foams react to aerosol sprays. From my experience, though, craft and eva foam are ok with it.
And just an added note, you can keep questions like this to your other thread asking for tips, as opposed to starting a new thread for each question . It's just good forum etiquette and keeps all of your info in one place!