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