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