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