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