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