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