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