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