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