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