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