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