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