G:=Group(
(1,2)(3,4)(5,13)(6,7)(8,9)(10,11)(14,15)(17,18),
(1,12,11,3)(4,17,6,5)(7,8)(9,10,15,16)(13,21,20,14)(18,19)
); 
F:=FreeGroup(2);
F:=F/[F.1^2,F.2^4,(F.1*F.2)^7,(F.1*F.2^2)^5,
             (F.1*F.2^-1*F.1*F.2)^5, (F.1*F.2*F.1*F.2*F.1*F.2^3)^5,
             (F.1*F.2*F.1*F.2*F.1*F.2^2*F.1*F.2^-1)^5];