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