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