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