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