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