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