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