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