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