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