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