Non-Transitive Grime Dice

From BoardGameGeek:

Each player picks a dice and whoever gets the highest value wins. Seems fair, but in fact you will always be able to pick a dice with a better chance of winning-no matter which dice you friend chooses first! If you play 'best of ten rolls' you'll be the champion almost every time. The dice are not weighted, they roll perfectly fairly. The secret lies in their unusual numbers. Non-transitive dice set discovered by Dr. James Grime of Cambridge University. This set has ten dice, two each of five different colors. When rolled singly, green tends to beat red, red tends to beat yellow, yellow tends to beat blue, and blue tends to beat purple. So you might think green is the best die and purple is the worst. But here is the twist: purple beats green, so there is no best! Even stranger, with two of each color (ten dice total), the order of which color beats which reverses direction. The set of ten includes color instructions and a cloth bag.