Frog in Akaka / Loango Région Gabon
I'm not completely sure as it's very difficult to determine frog species with just one picture taken from the side.
Morphology-wise it looks like this is a Afrixalis dorsalis, although it's colour doesn't comply with the most comomon pattern. You can find pictures of this species with specimen looking exactly the same or very similar.
Colour deviations occur in several frog species...

interesting article about frog species in Gabon
AmphibiaWeb Afrixalis dorsalis (this also mentions differences in patterns and light coloured populations)

Source: Wikimedia Commons


Source: http://calphotos.berkeley.edu


Common colours and pattern
Source: http://calphotos.berkeley.edu