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