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