Are FI spray paints safe for depron and blue styrofoam

....yes and NO!!!

I have experimentally painted foam by spraying it with these cans from a distance of 18 - 24 inches. Logic behind it is that by the time the atomised paint+thinner mixture reaches the depron, most of the thinner solvent evaporates and the paint gets deposited on the surface.

Try it at your own risk. I wouldn't.

Coat it with paper or tissue with 50-50fevicol and water ...post dry u can use spray paint....

OK . . . . can anyone tell me where to get testor's , kyrlon spray paints or enamel paint 
And...thank you Rastsaurabh and VC

go to any good hardware shop and ask for spray paints ... you will get the can for 120/- easily

I have not used spray paints till now.... I use Fevicryl fabric paints which are available in any stationery shop.... they are water soluble and stick well to the foam.  Once dried its water proof as it is acrylic based paint....

 this paint works on depron and blue styrofoam
and you apply it with brush 

Use Fevicryl (Rs 15 per small bottle) with a brush as suggested by Shobhit17 sir.
Or use coloured tape (Rs 35-40 per roll)

Also see build threads posted by umayash1 for fantastic intricate paint jobs on depron models.

I used to do fabric painting few years back, but haven't used on foam - will try and update.
Fabric paint (Acrylic) should work,It's available everywhere and is cheap.  good fabric artist can apply it better than a spray paint .

Acrylic fabric paint is cheaper if you buy as pack of different colors. I think Camaline is cheaper than Fevicryl .

_{Had to this post three times, as I was typing in dark}