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