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