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