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)(13,15)(17,21)(18,20)(19,22)(23,24)(25,26,32,38,31,37,30,36)(27,34,28,35,39,33,29,40)(1,3,7,4)(2,5,8,6)(9,11)(10,14)(12,18)(13,17)(15,21)(16,20)(19,23)(22,24)(25,27)(26,33)(28,32)(29,30)(31,39)(34,37)(35,36)(38,40)(1,4,7,3)(2,5,8,6)(10,15)(11,17)(12,19)(20,24)(25,28)(26,34)(27,32)(29,31)(30,39)(33,37)(35,36)(38,40)(1,5,7,6)(2,3,8,4)(9,12,13,19)(10,16,15,22)(11,18,17,23)(14,20,21,24)(25,29,31,28)(26,35,37,40)(27,30,39,32)(33,36,34,38)(1,6,7,5)(2,3,8,4)(11,17)(14,21)(18,23)(20,24)(25,30,31,32)(26,36,37,38)(27,28,39,29)(33,40,34,35)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.