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