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