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