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