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