I have done the same...although I wired 4 recessed cans and two sets of track lighting in my living room. I'm not sure what you meant by "use the diagram" but usually wires are painted when they are used for something other than what the general color coding would suggest, such as a white wire being used as the "hot" wire, when it is generally the neutral. I am not an electrician but I am under the impression that this is done to identify the wiring in case future extensions, etc. are needed. What I did was wire a normal dimmer to the source and then connected the whites to whites, blacks to blacks, and the grounds to grounds up in the boxes that are attached to the cans. Using this method you can't go wrong as far as I know. As long as you don't overload the circuit you should be fine, and 6 cans on a new 20 amp circuit should be ok.