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