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