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