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