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