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