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