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