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