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