I think JLD2.jl might be a good option:
julia> using Colors, JLD2
julia> x = rand(RGB, 3, 2)
3×2 Array{RGB{Float64},2} with eltype RGB{Float64}:
RGB{Float64}(0.8795,0.997088,0.0300252) RGB{Float64}(0.0860507,0.487816,0.772049)
RGB{Float64}(0.507044,0.239653,0.166532) RGB{Float64}(0.815468,0.1354,0.230995)
RGB{Float64}(0.847003,0.0561504,0.165049) RGB{Float64}(0.712974,0.591226,0.854261)
julia> save_object("color_file.jld2", x)
julia> x2 = load_object("color_file.jld2")
3×2 Array{RGB{Float64},2} with eltype RGB{Float64}:
RGB{Float64}(0.8795,0.997088,0.0300252) RGB{Float64}(0.0860507,0.487816,0.772049)
RGB{Float64}(0.507044,0.239653,0.166532) RGB{Float64}(0.815468,0.1354,0.230995)
RGB{Float64}(0.847003,0.0561504,0.165049) RGB{Float64}(0.712974,0.591226,0.854261)
julia> x == x2
true
There should also be more ways to save/load your data here: Basics · Julia Data Format