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