Over the last few years I've been working on a website to create, archive, access, modify wiring diagrams for guitar. This is a free tool and no need for downloading any software.
It features a library of components that you can access, and with the "Smart Wires" connect your components. This gives you a really clean way to keep track of your projects. http://guitarmodder.com/beta/
Some components, like the preamps are labelled "CAE Sound" , these components will be made to accommodate any wiring color codes and several preamps (Mike Walds, EMG, Graphtech, Your own, etc)
You can edit the way the wires are routed, Neat, tight, or Loose. This helps keep thing organized.
A few things to keep in mind-
-Best viewed in Safari or Google Chrome
-In order to save diagrams, you need to register
-More components will be added
-More features will be added
-"Save file to PDF" will be added
....you get the idea, its still a work in progress but it works.
Once you register,you can save the diagrams on the website, but to print or email diagrams, you will need to "Take a screen shot" of the diagram and save to your computer, for now.
Hers an example of a diagram.
I hope you get some use out of it, and feedback is always appreciated.