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)(27,37)(28,34)(29,39)(30,35)(31,36)(32,40)(33,38)(2,5)(6,8)(9,11)(10,14)(12,18)(13,17)(15,22)(16,21)(19,24)(20,23)(25,27)(26,33)(28,32)(29,30)(31,38)(34,35)(36,37)(39,40) involution — undirected(11,17)(14,21)(18,23)(22,24)(25,28,31,29)(26,33,36,37)(27,30,38,32)(34,35,39,40)(9,12,13,20)(10,15,16,19)(11,18,17,23)(14,22,21,24)(25,29,31,28)(26,34,36,39)(27,30,38,32)(33,35,37,40)(1,3,4,7)(2,6,5,8)(25,30,31,32)(26,35,36,40)(27,28,38,29)(33,39,37,34)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.