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