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