There is a standard way to convert a rewrite monoid into a finitely presented monoid using the function Relations. This is shown in the following example.
> FM<a,b,c,d> := FreeMonoid(4); > Q := quo< FM | a*b=c, b*c=d, c*d=a, d*a=b >; > M := RWSMonoid(Q); > Order(M); 11 > P<w,x,y,z> := quo < FM | Relations(M) >; > P; Finitely presented monoid Relations w * x = y x * y = z y * z = w z * w = x y^2 = w * z z^2 = x * w z * y = x^2 y * x = w^2 x * w * z = x^2 w^3 = w * z x * w^2 = x * z x^2 * z = x w^2 * y = w x^3 = x * w x^2 * w = z z * x = x * z y * w = w * y w^2 * z = y x * w * y = x