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