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