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