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