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