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