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