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