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