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