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