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