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