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