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