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