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