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