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