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