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)(25,26,31,35)(27,36,30,32)(28,34,29,33)(37,39,38,40)(1,2,5,4)(3,7,8,6)(10,16)(13,23)(17,20)(18,21)(25,27,31,30)(26,32,35,36)(28,37,29,38)(33,39,34,40)(2,4)(6,7)(9,11,15,12)(10,17,16,20)(13,18,23,21)(14,22,24,19)(25,28,31,29)(26,33,35,34)(27,37,30,38)(32,39,36,40)(9,12,15,11)(10,17,16,20)(13,21,23,18)(14,22,24,19)(25,29,31,28)(26,34,35,33)(27,37,30,38)(32,39,36,40)(1,3,5,8)(2,6,4,7)(9,13)(10,14)(11,18)(12,21)(15,23)(16,24)(17,22)(19,20)(25,26)(27,36)(28,33)(29,34)(30,32)(31,35)(37,40)(38,39)(1,4,5,2)(3,7,8,6)(9,14)(10,13)(11,19)(12,22)(15,24)(16,23)(17,21)(18,20)(25,30,31,27)(26,32,35,36)(28,37,29,38)(33,40,34,39)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.