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