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