To give you a simple answer, your clit is large and brown because it is. That's the way it came out of the oven. The only reason you would have any idea that this isn't a good thing is because big brown clits don't get a lot of callbacks for roles where clits are required.
A good rule when it comes to body parts is this: if it has a clear function (and let's face it, of all the functioning parts, the clit does one impressive job), we try to leave it alone. By this I mean we do our best not to let people who profit from visual prejudice near it with knives and scissors. If you feel like you just cannot get over the size of your clit, then sure, there are ways of changing that. See Dr. Gary Atler's site www.atlermd.com for clitoral reduction, featured just below vaginal rejuvenation. (Will someone please name their band this right now?) My opinion? Plastic surgery carries risks I don't think are fair to inflict on a body part whose sole duty it is to provide you with pleasure.