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