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