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