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