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