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