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