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