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)(25,26,31,35)(27,36,38,32)(28,29,33,39)(30,34,40,37)(1,2,5,6)(3,7,4,8)(9,11,16,23)(10,17,20,24)(12,21,14,13)(15,22,19,18)(25,27,31,38)(26,32,35,36)(28,30,33,40)(29,37,39,34)(1,3,5,4)(2,7,6,8)(9,12,16,14)(10,18,20,22)(11,21,23,13)(15,24,19,17)(25,26,31,35)(27,36,38,32)(28,29,33,39)(30,34,40,37)(1,4,5,3)(2,8,6,7)(9,13)(10,19)(11,12)(14,23)(15,20)(16,21)(17,18)(22,24)(25,28,31,33)(26,29,35,39)(27,30,38,40)(32,37,36,34)(9,14,16,12)(10,18,20,22)(11,13,23,21)(15,24,19,17)(25,29)(26,33)(27,37)(28,35)(30,36)(31,39)(32,40)(34,38)(9,15,16,19)(10,13,20,21)(11,22,23,18)(12,24,14,17)(25,30)(26,34)(27,33)(28,38)(29,32)(31,40)(35,37)(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.