The phrase "green coloring" usually refers to something that is green in color, like a drawing or object that has been colored with green paint or marker. Full definition
This cooking method will keep the beautiful bright green color of broccoli. (eugeniekitchen.com)
However if you plan to serve the guacamole within the hour, squeeze a bit of lemon juice to retain the bright green color of the avocado. (mindbodygreen.com)
Good quality but bought the dark green color in the pictures and received a much clearer tone of green! (amazon.com)