Back in the day, when printing costs were less expensive, cross-stitch companies would sometimes print the pattern that we use to stitch from in color. In other words, each square was printed in the color that it was to be stitched with. Sometimes there would also be a symbol in the same square. HOwever it is very difficult to use color when you need to use 75-100 different colors if you're doing a super-large, highly complicated pattern. And it can be very expensive for the designer/manufacturer. Most of the time, nowadays, patterns are done in just black and white with the different symbols tellling you where to place the various colors.
However, if you prefer a pattern in color, all you need to do is buy a good set of colored pencils (40 or so to a set) and color it yourself. I've done that a time or two. The only problem is when you need 6 colors of red and only have 3 red pencils. Then you just use another color.