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