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