Snake looks kind of dehydrated to me. When i got Pat home, I would hold a little bowl of water to him every few days to make sure he drank. I would also keep the humidity high for a week and be sure to place a lot of easily accessible water bowls so the snake doesnt have to look far. You can also mist the snake as they will readily drink off themselves and any plants or glass sides. I dont do it often as i want my snakes to get used to using water bowls.
Also i would inject the F/T feeders with a syringe of water every feeding. I do that with Pat and Alex and have had perfect 1 piece sheds from them every time.
And i would cover 3 sides of the cage to give the snake a feeling of security. Also cover 3/4 or more of the top. I use tin foil and it works well.
If that snake is a manok, it is younger than a year. They generally will start color changing around a year old. Biaks are the only ones that take forever and a day to change. Pat is about 1.3 years old and he is starting his change and he is a biak.
Also i would be worried about anyone who sexes a GTP under 1 year old. You might have gotten lucky but sexing that young can easily break or kink their spine as they are very fragile as babies.