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