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)(11,15)(12,17)(13,16)(14,18)(19,22)(20,24)(21,23)(25,26)(27,34)(28,32)(29,31)(30,36)(33,38)(35,40)(37,39) involution — undirected(2,5)(6,7)(9,11,14,20)(10,15,18,24)(12,19,13,21)(16,23,17,22)(25,27)(26,30)(28,36)(29,35)(31,39)(32,34)(33,40)(37,38)(10,16)(12,13)(15,22)(17,18)(19,21)(23,24)(26,31)(27,35)(29,38)(32,33)(36,37)(39,40) involution — undirected(1,3,4,8)(2,6,5,7)(9,12,14,13)(10,17,18,16)(11,19,20,21)(15,22,24,23)(26,32)(30,34)(31,33)(39,40)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.