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