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