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