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