Controlling/eradicating this invasive species takes effort - but the benefit of getting it off of your property and Colorado lands is worth it.
According to CSU, control requires an integrated approach, using biological, cultural and chemical methods. You can try flea beetles of the genus Apthona, which are available from the Colorado Department of Agriculture Insectary. Adults feed on leafy spurge foliage and larvae on roots resulting in weakened, less-competitive plants.
Sheep and goat grazing can significantly reduce leafy spurge if done during flowering (July) repeatedly over at least 3-5 years. Seed new grasses and avoid overgrazing of existing grasses to provide competition with the leafy spurge.
Most of us don't have large enough swaths (I hope) of leafy spurge, and so herbicide will be most effective for us. CSU has recommendations for best kinds of herbicides to use and methods of application in this link:
CSU Herbicide recommendations can be found here.