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