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