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