Paint just doesn't stick to that foam very well. Are you going to try to brush it or spray it? If I were you I think I would brush it. I would just go and get some Testors model paint. Or if you are good friends with a local taxi they could probably touch it up. I am an airbrush artist soI touch mine up with my airbrush and automotive paints. Good luck
I took an old hen decoy and gave it a sex change operation. I went to a craft store and bought tubes of tennis shoe paint. Kids use it to decorate their tennis shoes. It comes in any color you could possibily want. It will last you a season or two. I touch it up before the season.