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)(11,18)(12,26)(13,28,31,37)(14,21)(15,20)(16,22)(17,24)(19,30,36,29)(23,38,39,32)(25,33)(27,35,40,34)(1,3,5,8)(2,6,4,7)(9,11)(10,17)(12,14)(13,27)(15,24)(16,25)(18,21)(19,35)(20,33)(22,26)(23,29)(28,32)(30,39)(31,40)(34,36)(37,38)(1,2,5,4)(3,6,8,7)(9,12,14,11,16,24,15,25)(10,18,20,26,22,33,21,17)(13,27,30,23,31,40,29,39)(19,34,37,38,36,35,28,32)(1,4,5,2)(3,6,8,7)(9,13,16,31)(10,19,22,36)(11,23,25,39)(12,27,24,40)(14,30,15,29)(17,32,26,38)(18,34,33,35)(20,37,21,28)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.