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