The Treasure of Color dungeon drops relics that you can use to make room furniture. If you don't have a room yet see the "My Room Guide" NPC in Revere (or any other base). The following is a list of the relics found in this dungeon, which portals you take to get them, and the floor reward box.
Relic Name> path to take > Box # in Reward Room
Smooth Cloth > Right, Left, Left > Box 12
Unique Design > Right, Left, Right > Box 13
Mysterious Metal > Right, Right, Left > Box 14
Shiny Stone Material > Right, Right, Right > Box 15
High Class Feather > Left, Left, Left > Box 8
Precious Wood > Left, Left, Right > Box 9
Mana Stone Piece > Left, Right, Left > Box 10
Colorful Glass > Left, Right, Right > Box 11
Furniture Recipe > any path > Box 8 to 15
Mysterious Seed > Any Path/Right > Box 1 & Box 3
Fountain Watering Can > Any Path/Right > Box 1 & Box 3
If you don't need large amounts of any one relic, “Box 1” & “Box 3” contain a few of all the relics except for Furniture Recipe. Furniture Recipe 2 and 3 can be created at Synthesis. Creating furniture with materials gives you experience points towards your housing level. Raising your housing level unlocks more furniture options etc.
Please note:
I have not tested the option "Create by Gold" to see if it raises housing level. Previously, (in 2016) getting furniture by spinning in shop, and the option "Purchase Furniture," did not raise housing level.
If you are unsure how to follow the directions above perhaps this example will help:
You need a lot of Precious Wood. The path to Precious Wood is LEFT, LEFT, RIGHT. The first room of the dungeon would be floor 1. After defeating the mobs on floor 1, take the portal on the LEFT to floor 2. Defeat them, and take portal on the LEFT to go to floor 4. Complete floor 4 and take the portal on the RIGHT to floor 9. On floor 9, you will find the boss Albero. He only drops Precious Wood & Furniture Recipe. His drops would be in the Reward Room in Box 9. The mob drops from floors 1, 2 & 4 (found in Box 1, 2, & 4) are various furniture relics from potential paths.
Happy decorating!