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