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