Why is a black iPhone 4S is shown as white in iTunes?
iTunes deduces the color of the iPhone from the serial number he finds on the logic board. For example:
MD269LL = Black AT&T 64GB 4S
MD271LL = White AT&T 64GB 4S
MD277LL/A = White Verizon 16GB 4S
...
So, check your model number and look it up to make sure you've got a black one.