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