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