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