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