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