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