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