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