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