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