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