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