The route is described in detail with small maps in next Cicerone guide: Last modified December 2009
West Highland Way: Books
The West Highland Way - from Milngavie to Fort William by Terry Marsh
The route is waymarked well, so the maps in the guide give enough information. In the booklet the route is divided in several stages. You can stick to that, but you can also make your own division, like we did.
Next to the Cicerone guide we used, there are several other guides that describe the route, like the guides of Rucksack Readers and Trailblazer, and stripmaps of Footprint and Harvey.