Nontrivial semidirect product of Z3 and Z8

Definition
This group is defined as the external semidirect product of cyclic group:Z3 by cyclic group:Z8, where the generator of the latter acts on the former via the inverse map. Explicitly, it is given by:

$$\langle a,x \mid a^3 = x^8 = e, xax^{-1} = a^{-1} \rangle$$

where $$e$$ denotes the identity element.

Description by presentation
Here is a description using the presentation given in the definition:

gap> F := FreeGroup(2);  gap> G := F/[F.1^3,F.2^8,F.2*F.1*F.2^(-1)*F.1];