PaintboardScript

local colours = {Color3.fromRGB(223, 223, 222), Color3.fromRGB(255, 0, 4), Color3.fromRGB(255, 119, 0), Color3.fromRGB(255, 226, 0), Color3.fromRGB(123, 255, 0), Color3.fromRGB(0, 213, 255), Color3.fromRGB(0, 55, 255), Color3.fromRGB(255, 0, 255)}

for i, canvasBlock in pairs(script.Parent:WaitForChild("Canvas"):GetChildren()) do

    canvasBlock.Color = colours[1]

    local clickDetector = Instance.new("ClickDetector", canvasBlock)

    clickDetector.MouseClick:Connect(function()

        local currentColourIndex = table.find(colours, canvasBlock.Color)

        local nextColourIndex = currentColourIndex + 1

        if nextColourIndex > #colours then nextColourIndex = 1 end

        canvasBlock.Color = colours[nextColourIndex]
    end)
end