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