The paint codes are pretty much manufacturer specific so you need to decide which brand you want to use. They can be cross referenced.
The XX1 tractors used an orange red color. The PPG code for the orange red is 71346. The gray should be 30448, but I would check it out first. If you go with Martin Senor (sp) paint, I believe Napa probably has a color chart for tractors.
If you go to your local CNH dealer you can buy spray cans of the colors, paint a piece of metal and then have it matched. They also sell in quart and gallon size. I believe they use and acrylic enamel.
Hope this helps.