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