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