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