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