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