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