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