Black and white ,are all seasons black and white?

Yes, all 7 seasons of "Cheyenne" were filmed in black and white.

as the other poster notes it was all B&W...

it is my recollection it wasn't until Mid 60s that Everyone got on the 'Now in Color' bandwagon

according to wiki

"The first national color broadcast (the 1954 Tournament of Roses Parade) occurred on January 1, 1954, but during the next ten years most network broadcasts, and nearly all local programming, continued to be in black-and-white. It was not until the mid-1960s that color sets started selling in large numbers, due in part to the color transition of 1965 in which it was announced that over half of all network prime-time programming would be broadcast in color that fall. The first all-color prime-time season came just one year later."

so anything Pre-1954 'had to be B&W' and until '65 it was still a Toss up, because not enough households even Had a Color TV to take advantage of the Film yet... heck Digital/HD TV in the modern age took almost as long... heck I would not be shocked if a few shows still broadcast in Standard Definition