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