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