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