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