For a contractor? Are you a client wanting to hire a web designer? If that is the case they should be the ones providing the contract Are you a web designer wanting to take on a contractor? If that is then are you employing them on an hourly rate or fixed price? If its the former then its just a normal contractor contract you want and the web design bit is irrelevant. If its the later then you could either use their standard contract or a slightly rewording of your own contract that you use for fixed price jobs would surfice, just put yourselves as the client and the contract as the supplier
My user name will tell you that I have an obvious bias here, but I think if you are in business then your standard forms should at least be reviewed by a knowledgeable attorney. When you grab a form from somewhere, even if it seems very good, it may be inappropriate to your particular circumstances. If you are a web designer, the amount that you pay for a clearly written basic contract covering your terms, which can be used over and over again, will usually be a bargain compared to the amount it will cost you in problems and client disputes if you don't have one.