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