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