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