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)(25,26,30,28)(27,32,35,31)(29,36,38,33)(34,39,37,40)(10,14)(15,20)(16,21)(22,24)(25,27,30,35)(26,31,28,32)(29,34,38,37)(33,39,36,40)(5,6)(7,8)(9,10)(11,15)(12,16)(13,14)(17,20)(18,22)(19,21)(23,24)(25,27)(26,32)(28,31)(29,37)(30,35)(33,39)(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)(25,28,30,26)(27,31,35,32)(29,36,38,33)(34,39,37,40)(9,12)(10,16)(11,18)(13,19)(14,21)(15,22)(17,23)(20,24)(25,29)(26,33)(27,34)(28,36)(30,38)(31,39)(32,40)(35,37) involution — undirectedA 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.