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