If you could post pictures that would help, also make sure of your building's codes/rules, keep in mind weight, drainage, exposure (sun/wind/light), privacy concerns, lighting, etc. and consider getting professional design help for someone who specializes in roof gardens. You don't have to do everything all at once but a design professional could help you clarify your vision and give you ideas you may not have even thought to incorporate. Best of luck, 800 sf of outdoor space is wonderful. Don't forget you've got to get everything up to this space too.

Siraj, sharing few pics would help the imagination.

Fh cnm

Go for white shades which has hint of green (example Absolute white L161 Asian paints) as there are lot of dark colored elements here and needs to be balanced out and is also good as per vastu. I really like thw furniture and small wall decor you have here.. but I really feel it is underutilized. A good interior designer can really turned around this room with very less expenses and modifications. Please message for any further queries and let me know if my suggestion helped you.  Regards ὠ0