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