Absolutely! So long as your not leaving the iron in one spot for too long or pressing into the foam particularly hard, you'd be able to cover foam in whatever color you want. However, make sure that your glue will actually stick to the covering. Hot glue WILL NOT HOLD to plastic coverings like monocote or even packing tape. You'll need to cut away the covering where you want to glue to get a good hold strength.
Hope this helps, good luck.