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