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