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