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