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