Hi,
I wanted one of the railroad Tornados, but hate the colour it comes in and thought I would go this route of livery, as with all pictures it is hard to guess the correct colour, but I think it's close to Humbrol 127 ghost grey, used in US warships.
If you do get the exact colour, please post, we would love to know.
Another thought I've just had, you could try taking the photo to a body shop, they will usually mix a can for a few quid.
All the best,
Mark