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