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