My schematic was very similar to the one suggested by https://www.hwhardsoft.de/english/projects/simon-says/ with some minor changes related to the voltage regulator. Because I intended to get the PCB manufactured I needed to get some PCB design software.
I used a piece of software called Fritzing which can be downloaded from fritzing.org for free. 
Once installed, learning to use the software was pretty strait forwards. I think it probably took me 5 or 6 hours to get my head around the software and then around a day (probably a long day) to design the board.
The final version looked like this.
The final PCB design looked like this in Fritzig.
The link below contains my final files ready to be submitted for manufacture.
Zip file containing Simon PCB design files.
Getting the PCB made was really simple. I went to https://aisler.net/fritzing/ and simply uploaded my .fzz file.
After about 10 days my PCB arrived, and I was delighted!. The quality is excellent, it is amazing you can get these made in such short runs.
