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