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