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