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