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