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