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