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