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