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