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