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)(11,17)(12,16)(13,15)(14,19)(18,24)(20,22)(21,23)(25,26)(27,35)(28,33)(29,34)(30,32)(31,38)(36,37)(39,40) involution — undirected(9,11,13,19)(10,14,15,17)(12,20,21,18)(16,24,23,22)(25,27,29,38)(26,31,34,35)(28,37,30,39)(32,36,33,40)(2,5)(6,8)(25,26)(27,36)(28,32)(29,34)(30,33)(31,39)(35,37)(38,40) involution — undirected(1,3,4,7)(2,6,5,8)(10,15)(14,17)(16,23)(22,24)(25,28,29,30)(26,32,34,33)(27,37,38,39)(31,36,35,40)(9,12,13,21)(10,16,15,23)(11,18,19,20)(14,22,17,24)(25,28)(26,33)(27,38)(29,30)(31,35)(32,34)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.