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