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