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