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