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