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