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