What color(s) would Earth be without water or life? Many of the celestial bodies in our solar system have well-established color schemes, at least in the minds of the public.  Mars is pale-red and black, Venus (beneath the clouds) is generally shown in rich yellows and oranges, the Moon ranges from dark to light gray, etc.

And, of course, Earth is famously blue and green.  However, this is entirely because of the presence of large oceans and life.  We're not seeing Earth's geology represented in these colors, as we are with the other planets, we're seeing overlaid colors from other processes that don't apply to Mars, Venus, or the Moon.

So I'm wondering, if you stripped away life and the oceans, what color(s) would Earth be?  Based on types of rock, etc.  Would the seabed be a different color from the continents?  Would it be more uniform, or would it vary in color quite a bit from region to region?  Would it be a similar gray to the Moon, or would other chemical processes (like the rusting of Mars) give it a more unique palette?
That's actually an interesting question. Let's try to answer it, but first let's make a few assumption.


Oxygen on Earth is biogenic, so without life there would be no oxygen. However, let's assume that some magical process keeps the oxygen in the atmosphere.
Oceans play an important role in plate tectonics, and without it it might change. Let's assume that plate tectonics keep on running regardless of the state of the oceans.


The majority of the Earth's surface is covered by oceanic crust. This crust is composed of basalt, an iron rich rock. This iron would rapidly oxidise and rust, giving a red tint (possibly Mars-like) to most of the Earth's surface. The mid ocean ridges will most likely be black, but it will get redder the farther you get away from there.

The continental crust would like slightly different. Mountain ranges would appear grey, perhaps slightly pinkish - not too different from the highest peaks you see today. Most of the continental crust is composed of granite (sensu lato), a grey-pinkish rocks. Because there's no life and no vegetation, that barren landscape you see high above the mountains would go all the way down to the base of them mountains. At the mountain's base, you would get deserts of quartz sand, slightly yellow. Think the sand dunes of the Sahara desert. This sand comes from the breakdown of the granites. Quartz, the most resistant mineral in the granite forms sand, I guess from the action of wind. The other minerals (mostly feldspar) break down to form all kinds of clays, aka dust.

So to sum it up:

Most of the surface will be covered by dark red low lands, with high lands of sandy desert and Himalaya type mountain belts sticking out of them.