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