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