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