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