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