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