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