seven shades of

Reader's Digest 8月号のMy Storyの記事からの引用です。
While standing at ease, we all turned to check on Tommy. None of us were lost to the poignancy of the moment - except the sergeant major, who found this unplanned movement in the ranks totally unacceptable. Showing seven shades of fury, he called the entire band out for punishment drell in full view of the Army and Air Force.
"seven shades of fury" の "seven shades of" は慣用句の様です。しかし辞書で調べたが "seven shades of" と言う慣用句はなく、 "beat seven shades of shit" と言うスラングの慣用句があることが分かりました。
・Dictionary of Slang: To thoroughly beat up. Also, less commonly, beat seven kinds of shit out of (someone). Cf. 'kick seven shades of shit out of (someone)'
多分このスラングを念頭にした表現でしょう。