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