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