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