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