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