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