One vertex per element, one color per generator, with an edge from x to x·s.
(3,7)(6,8)(9,10,13,17,14,19,21,18)(11,20,23,15,24,29,34,30)(12,16,27,25,26,31,35,32)(22,33,38,28,37,36,40,39)(2,5)(3,7)(9,10)(11,15)(12,25)(13,18)(14,19)(16,27)(17,21)(20,23)(22,36)(24,30)(26,32)(28,38)(29,34)(31,35)(33,37)(39,40) involution — undirected(1,2)(3,6)(4,5)(7,8)(9,11,21,34,14,24,13,23)(10,15,17,29,19,30,18,20)(12,22,35,40,26,37,27,38)(16,28,25,36,31,39,32,33)(2,5)(6,8)(9,12,21,35,14,26,13,27)(10,16,18,32,19,31,17,25)(11,22,34,40,24,37,23,38)(15,28,20,33,30,39,29,36)(1,3,4,7)(2,6,5,8)(12,26)(16,31)(22,37)(25,32)(27,35)(28,39)(33,36)(38,40)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.