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