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