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