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