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