From the TICA Savannah Standard

COLORS:

Black, brown spotted tabby, silver spotted tabby, black smoke ONLY. The only color variations allowed are the gold to orange ground color with bold dark markings, the silver ground color with bold dark markings or solid black. In any variation the lips are black, as are the prominent black tear duct lines on the inner sides of each eye.

On the spotted Savannahs the nose leather can be either brick red, solid black or black with a light red or pink line running down the center. In black Savannahs, the nose leather must be solid black. Paw pads in either color variation should be deep charcoal or brownish black.

Due to the unique breeding programs of so many of the Savannah breeders, other, non-standard, colors will be seen in and amongst the standard colored Savannahs in some litters. These kittens of non-standard color, many times, have the same great looks, intelligence and personality of any Savannah. These non-standard colors do NOT make the Savannah less of a Savannah however these cats should not be used in a Savannah breeding programs and therefore many responsible breeders will place them in pet homes and most times will discount the price somewhat to ensure they do find a loving home.

Below are pictures of Savannahs that represent the accepted colors.

Black - Lustrous jet black, with sound color from roots to tip of fur. Many black Savannah's spotting will show in certain light. This is not a penalty for the Savannah breed.
Brown Spotted Tabby - Pattern to be black; ground color ranging from a rich tawny brown, tan or yellow to a cold beige color depending in the amount of rufousing present. Several examples are shown above for the brown spotted Savannah due to the tremendous variation that occurs in this color.
Silver Tabby - The ground color should be pale silver with jet black markings or tipping.
Black Smoke - Cat should appear jet black with a silvery white undercoat. The undercoat of the head, face, legs, back, sides and tail does not show until the coat is parted. The belly and underside of the tail may appear gray, shading down to the silvery white.