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