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