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