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