For the 拗音 starting with //k-//, and for speakers familiar with English, think of the name of the letter Q. This is the same kind of 拗音, and is quite close to the pronunciation of the Japanese kana combination きゅ. So for the other vowel values, think about using the same mouth shapes as Q to start, and just change the ending vowel.
For the 拗音 starting ...
The counter for color is 色（しょく）. If you want to say "seven (different) colors" without any idiomatic meaning, you can say ななしょく.
to paint a map using seven different colors
When you say like this, the colors can be anything including gray, brown and pink. Alternatively, you can just say 7つの色【いろ】.
The word 七色【なないろ】, in kanji, ...