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