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