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