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