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