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