The factory color for the 140s was all red. I have seen many that were purchased for industrial applications that were painted Yellow from the factory, similar to the Industrial A tractors that were offered in Yellow from the factory, along with solid front axles, and other industrial options.
IH would paint the tractors almost any color that a customer wanted. I have seen photos of orange ones, but never saw a white one.
The Farmall A, C, M, and H all had a Demonstrator series in 1950, along with the Cub. I have a friend that has a white demonstrator Super A, and have seen many potos of the others. Again, like the Cubs, these were most likely painted red before selling to customers.
The 140s are basically the same tractor as the Super A, but came out in the 1960s, and I do not believe that there was ever a Demonstrator series in the 1960s, other than the gold demonstrator 14XX tractors in the late 1960s. I'm sure Jim Becker will be able to provide more details.