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