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