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