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