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