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)(28,37)(29,39)(31,34)(32,35)(33,40)(36,38)(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)(26,28)(29,31)(30,35)(32,37)(33,34)(36,40)(38,39) involution — undirected(1,3)(2,5)(4,8)(6,7)(25,28,32,30)(26,27,35,37)(29,38,40,34)(31,33,36,39)(9,10)(11,14)(12,15)(13,16)(17,21)(18,22)(19,23)(20,24)(25,29)(26,33)(27,36)(28,38)(30,34)(31,37)(32,40)(35,39) 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)(25,30,32,28)(26,27,35,37)(29,34,40,38)(31,33,36,39)(1,2)(3,5)(4,7)(6,8)(9,12,13,20)(10,15,16,24)(11,17,18,19)(14,21,22,23)(25,31,32,36)(26,34,35,38)(27,29,37,40)(28,33,30,39)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.