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