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