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