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