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