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