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