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