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