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