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