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