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