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