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