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