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