I highly recommend "Landscapes of Madeira, by Pat and John Underwood" Sunflower books ISBN 1-85691-200-0.
The book has been written specifically for walking, picnics or short walks using your car, plus dedicated car tours, which guide you by road, to elite locations. All maps are included, car tours and walks are illustrated with colour pictures and detailed easy to follow instructions that "actually explain" how to get to your destination. Even bus timetables are provided. There are several bus companies offering coverage of the entire island. The guide provides a map showing where to get the busses in Funchal (see main town map page) and which colour bus you need to take you to your choice of destination (various bus companies have different colour busses).
The additional information provided is carefully inserted so as to avoid confusing the all important walking instructions. I have purchased many guide books over the years and this is the FIRST book that ever inspired total confidence! My experience proved that nothing else was required.
We based our entire holiday on this book. The only thing I will gain from recommending it is the pleasure of knowing you will have a fantastic holiday - it is "Madeira's bible".
I could not ask for more from a guidebook than Pat and John Underwood offer in their Sunflower guide and consider it to be the essential and "reference standard" in walking guide books.