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