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)(26,32)(28,33)(34,39)(36,40) involution — undirected(1,2)(3,8)(4,6)(5,7)(9,11)(10,13)(12,20)(14,18)(15,17)(16,24)(19,22)(21,23)(25,26)(27,28)(29,33)(30,34)(31,32)(35,36)(37,40)(38,39) involution — undirected(1,3,5,6)(2,4,7,8)(10,15)(11,18)(16,23)(19,20)(25,27,31,29)(26,28,32,33)(30,35,38,37)(34,36,39,40)(9,11)(10,13)(12,19)(14,18)(15,17)(16,21)(20,22)(23,24)(25,28,31,33)(26,27,32,29)(30,36,38,40)(34,35,39,37)(1,2)(3,4)(5,7)(6,8)(9,12,14,22)(10,16,15,23)(11,19,18,20)(13,21,17,24)(25,29,31,27)(26,33,32,28)(30,35,38,37)(34,36,39,40)(1,4)(2,6)(3,7)(5,8)(9,13)(10,11)(12,21)(14,17)(15,18)(16,19)(20,23)(22,24)(25,30,31,38)(26,34,32,39)(27,35,29,37)(28,36,33,40)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.