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