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