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