Since I didn’t use expressions to make all colors editable from one layer in main composition, you’ll have to edit them manually. But it’s easy, it will take just a moment for you.
To change colors of the texts, just select all text layers and change the color in character window. You have to do this three times, each time for texts in different compositions – composition Main Part1, Main Part2 and Main Part3 compositions.
Other elements have editable colors in compositions:

• Color Gradient1 – layer Ramp Overlay has Tint effect applied, change color of the Tint’s “Map White To” to little dark version of color you want to use.
• Color Gradient2 – same layer, same effect, change it to light version of color you want to use.
• Big Circle Final – there is only one layer in this comp, has applied Ramp effect, change the color of Ramp’s “Start Color”
• Big Line – only one layer is inside, has Tint effect applied, change its “Map Black To” color to whatever you need.

I hope this helped you, if you need further help, contact me throug my profile page.