There is one located west of the Fizztop Grille, on the large wall beside the restrooms building.
There are two in the Safari Adventure. The first Cappy in is through the hedge maze beneath the treehouse, against a wall on the eastern edge. From the entrance, the order of turns is: right, right, left, left, and right. The second is just outside the primate house, on the back of the gorilla statue to the right of the door. There is a patch in the hedge where one can pass through.
Dry Rock Gulch
There are two in Dry Rock Gulch. The first is located on the back of a gravestone next to the Giddyup Kid Protectron. The second is inside Mad Mulligan's Mine, on the wall of a little shack beside the waterfall.
There are two in the Galactic Zone. The first is at the entrance to the dead traders' camp around the back of Star Control entrance. The sign should be on the left side entrance, right next to the Employees Only sign at the gate. The second is up the ramp right next to the exit door of the RobCo Battlezone. Turn right immediately at the top of the Spacewalk ramp, and the Cappy is on the right wall near the trash bins.
There are two in the Kiddie Kingdom. One is in the Fun House in the turntable room, second door on the left when entering from the topsyturvy room. The second is located just before the moat to King Cola's Castle, on the top floor of the damaged red tower to the left, letter I.
World of Refreshment
There is one in the World of Refreshment. Inside the plant, following the Nuka-Cola Quantum river, it is on the side of a two story building across from the Nuka Wild sign in the Wild West setting. Going in the opposite direction that was intended for the ride helps one spot it easily, it will be on the right hand just as one enters the Wild West setting from the 'wrong' direction.
G / R / E / N / F / I / E / H / R / S
Putting the hidden Cappy clues in the right order results in "REFRESHING," as stated by Sierra Petrovita.