One vertex per element, one color per generator, with an edge from x to x·s.
(2,5)(3,7)(6,8)(9,10)(11,19,22,15)(12,23)(13,27)(14,17)(16,26)(18,24)(20,35,37,40)(21,30,36,34)(25,33)(28,32)(29,38,31,39)(1,2,4,6)(3,8,7,5)(9,11,13,21,14,22,24,36)(10,15,27,34,17,19,18,30)(12,20,28,39,25,37,26,38)(16,31,23,35,32,29,33,40)(1,2)(3,8)(4,6)(5,7)(9,12,24,26,14,25,13,28)(10,16,18,33,17,32,27,23)(11,20,36,38,22,37,21,39)(15,29,30,35,19,31,34,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.