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)(26,30)(31,33)(32,39)(34,40)(1,3,5,4)(2,6,7,8)(9,11)(10,14)(12,18)(13,19)(15,22)(16,17)(20,23)(21,24)(25,26,28,30)(27,34,35,40)(29,31,37,33)(32,36,39,38)(1,4,5,3)(2,6,7,8)(26,31)(29,37)(30,33)(32,40)(34,39)(36,38)(9,12,13,21)(10,15,16,20)(11,18,19,24)(14,22,17,23)(11,19)(14,17)(18,24)(22,23)(25,27,28,35)(26,32,30,39)(29,38,37,36)(31,40,33,34)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.