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