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