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