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