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)(11,21,26,38)(12,27,29,36)(13,17,30,18)(14,31,22,19)(16,32,35,25)(23,33,28,34)(24,40,39,37)(1,3,5,4)(2,6,7,8)(9,11,22,32,15,26,14,25)(10,16,31,38,20,35,19,21)(12,28,30,39,29,23,13,24)(17,33,36,37,18,34,27,40)(1,4,5,3)(2,6,7,8)(9,12,15,29)(10,17,20,18)(11,23,26,28)(13,14,30,22)(16,33,35,34)(19,36,31,27)(21,37,38,40)(24,32,39,25)(9,13,14,29,15,30,22,12)(10,18,19,36,20,17,31,27)(11,24,25,23,26,39,32,28)(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.