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