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