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