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