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