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