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