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