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