Where do papayas get their yellow color?

Papayas contain several different brightly colored carotenoids, and yellow papayas in particular contain a significant amount of the yellow compound beta-carotene. Beta-carotene is found in many other yellow fruits and vegetables, including squashes and carrots.
Beta-carotene is a precursor to vitamin A, also known as retinol, a vitamin that is essential for vision as well as other aspects of health. We humans are able to convert beta-carotene to retinol, therefore we are able to use the beta-carotene as a source of vitamin A. Interestingly, while vitamin A is toxic in large amounts, fruits and vegetables containing beta-carotene are considered a safe source of vitamin A, because our bodies convert only as much beta-carotene to retinol as we need. Eating an excess of beta-carotene can, however, cause our skin to appear yellow! This condition is harmless and goes away if we reduce our beta-carotene consumption.