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