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