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