Let ▫G▫ be a transitive group of odd prime-power degree whose Sylow ▫p▫-subgroup ▫P▫ is abelian od rank ▫t▫. Weshow that if ▫p>2t−1▫, then ▫G▫ has a normal subgroup that is a direct product of ▫t▫ permutation groups of smaller degree that are either cyclic or doubly-transitive simple groups. As a consequence, we determine the full automorphism group of a Cayley diagraph of an abelian group with rank two such that the Sylow ▫p▫-subgroup of the full automorphism group is abelian