Like therriman said, it all depends on what era you are making your Missouri. I am taking a stab at it, but I would guess you are building a WWII-era ship. That seems to be the more popular time. Well here is a site I got from another thread that lists what camo schemes your ship was wearing at different times during WWII:
http://www.shipcamouflage.com/usn_bb.htm
Once you get what scheme you want to paint, hit the "Camouflage Measures" button on the left to get a rundown of what and where the colors were placed. And here is a site that will translate those color codes into actually paints:
http://battleships.freewebsitehosting.com/Camo.html
You have to hit that site up early in the day, because they have a data-transfer limit, which when exceeded shuts the site down for the rest of the day. Have at it and good luck.