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