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