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