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