Jellies can be any color.
Jelly fish are mostly made of water but they can have pigments or even symbiotic algae. This means that some species of jelly fish are clear and others have colours.
Jellyfish come in a big variety of colors. They are white, blue, pink, yellow, green, purple, red, orange, and striped. Each one of those colors represents the same thing. They are all bright colors and tell their enemies that they are dangerous fish.
Jellyfishes are translucid, however some of them can have coloured parts with red, pink or yellow pigments or with microorganisms inside them, which give green, brown or blue colorations. Pigments, usually, give red, pink or violet colourations. * Mycroorganism like zoochlorellae are greenish. * Zooxanthellae are brownish. * Some blue colourations can be dued to the presence of Cyanobacteria. Some jellyfishes, like Pelagia noctiluca or some Trachymedusae, are bioluminescent and can emitt greenish or multicoloured flashes.