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