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