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