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