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