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