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