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