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