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