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