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