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