Here's a general idea:
* Brown: This is the most common color due to the presence of plant matter in their diet.
* Black: This could indicate a diet rich in dark fruits or a digestive issue.
* Green: This may occur if the monkey has consumed a lot of green leafy vegetables.
* Yellow: This could be a sign of diarrhea or other health problems.
It's important to remember that the color alone isn't a definitive indicator of health. If you observe unusual changes in a monkey's feces, it's best to contact a veterinarian or animal expert.