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