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