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)(16,22)(17,26,33,25)(21,36,38,30)(23,31)(29,32)(35,37,40,39)(2,6)(3,4)(7,8)(9,11,13,22,15,23,14,29)(10,16,18,20,19,32,28,31)(12,21,26,39,27,38,25,37)(17,30,34,35,33,36,24,40)(9,12)(10,17)(11,21)(13,26)(14,25)(15,27)(16,30)(18,34)(19,33)(20,35)(22,39)(23,38)(24,28)(29,37)(31,40)(32,36) involution — undirected(2,7)(6,8) 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.