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