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