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