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