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