The CB&Q called their caboose, Way Cars.
They were painted in silver, green, chinese red, and box car red.
They also had many styles from the NP wide vision type to shacks on a flatcar type. But, for your locomotives they had a pretty unique wooden style that had four windows with cross braces in them. It is sometimes called the CB&Q caboose.
I believe for your locomotives the caboose red or chinese red ones would be appropriate. Walthers makes this exact model individually or in a set. http://www.walthers.com/exec/productinfo/932-7562
I prefer the box car red ones. http://www.walthers.com/exec/productinfo/932-7568
They also come in FW&D and C&S flavors.
Correct CB&Q cabooses (waycars) are available from both Walthers (plastic RTR) and AMB (wood semi-craftsman kits). AMB offers three different CB&Q cabooses, all of which build into much more accurate models than the Walthers caboose (if that’s important to you)
The CB&Q, especially in the later years (1960-1970) had a dizzying array of caboose colors. The default caboose colors for the steam era were either boxcar red or caboose red. Silver, yellow, orange and white were mostly post-steam era colors, and the BN green cabooses were painted only a couple of years before the creation of the Burlington Northern.
I went to my local hobby store here in Houston, Papa Bens and bought a Walthers CBQ-FW&D caboose red caboose, sure is sharp. It will look great on the tail end of my CBQ 4-8-4.