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