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