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