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