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