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