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