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