I discovered XCircuit when looking for an easy and quick way to generate a schematic.
Since I am not going to simulate it, it would be enough to have a vector design program like Inkscape, but it’s never too late to learn a tool that may prove useful in the future.
(…)program for drawing publishable-quality electrical circuit schematic diagrams and related figures(…)
— XCircuit website
In this post you’ll find a quick overview of XCircuit, and how to create a module with it.