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