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