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