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