The actual colors of Uranus and Neptune are quite similar. Some of the images of Neptune from the Voyager 2 flyby (in 1989) show a deep blue color, but the colors in those images were enhanced. Neptune would appear darker than Uranus due to dimmer illumination (greater distance from the Sun). As in the case of Uranus, the color is due to methane. In some photos released after the Voyager 2 flyby (in 1986), Uranus looked green, but that color was artificial. This gives the rest of the atmosphere more of a chance to scatter light, just like the Earth's atmosphere does. Scientists think that because the rings are blocking the Sun in the winter hemisphere, things are colder there and the ammonia clouds are lower down than normal. Clouds in Saturn's winter hemisphere are pale blue. White ammonia haze covers the whole planet and partially obscures redder clouds below. None of the four 'gas giant' planets (Jupiter, Saturn, Uranus, and Neptune) has a solid surface, so all we see are just clouds in their atmospheres. The white bands are colored by ammonia clouds, while the orange comes from ammonium hydrosulfide clouds. The dominant reddish color comes from rusty rocks on the surface, since the clouds are rare and thin. Mars: mostly reddish brown, though with some darker regions, and also white ice caps.Earth is by far the most dynamic planet when seen from space. Depending on the area seen in an individual picture, brown, yellow and green continents can be seen or parts of Earth can be covered by white clouds. Oceans and light scattered by the atmosphere make Earth prevailingly blue. You can find more on the colors of Venus here. The colors from those Venera images were later used to colorize radar data from NASA's Magellan spacecraft, in order to generate simulated global views of the surface of Venus. Two of the Soviet Venera probes returned images from the surface of Venus. We can only see the thick layer of featureless sulfuric acid clouds. To human eyes, Venus looks kind of boring. Mercury's color variations are fairly subtle the color variations are greatly exaggerated in this false color view. Note that many images of Mercury (like this one) are grayscale, derived from a single color filter. Mercury has practically no atmosphere, so we just see the rocky surface. (Note that spacecraft photos appearing in the media often have false coloration.) Here are the true colors of the planets, with links to some relevant images from NASA spacecraft. What are the true colors of each planet in our Solar system? I've seen the same planet colored differently in different photos.

Mercury color