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