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