Color is a good, but not an exclusive, indicator of phytochemical content. Many, but not all, phytochemicals are pigments that give plants color. Some phytochemicals are colorless, and some are responsible for taste. Sometimes one color, green especially, can mask another color that is in the vegetable. Even products in one color group will have varying amounts of the same phytochemical.
Bottom line: eating a variety of fruit and vegetable colors is important to get all of the nutrients they provide. Try to ‘eat a rainbow’ of fruits and vegetables every day for optimal nutrition.