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)(11,15)(12,16)(13,14)(17,23)(18,21)(19,24)(20,22)(26,31)(27,32)(33,39)(34,37)(1,3,5,8)(2,6,4,7)(25,26,30,31)(27,28,32,35)(29,33,38,39)(34,36,37,40)(1,4,5,2)(3,7,8,6)(10,14)(15,21)(16,22)(23,24)(26,31)(28,35)(33,39)(36,40)(9,11,13,18)(10,15,14,21)(12,19,20,17)(16,24,22,23)(25,27)(26,28)(29,37)(30,32)(31,35)(33,40)(34,38)(36,39)(9,12,13,20)(10,16,14,22)(11,17,18,19)(15,23,21,24)(25,28)(26,32)(27,31)(29,36)(30,35)(33,37)(34,39)(38,40)(9,10)(11,15)(12,16)(13,14)(17,23)(18,21)(19,24)(20,22)(25,29,30,38)(26,33,31,39)(27,34,32,37)(28,36,35,40)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.