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