From UroWiki
Uromastyx vary widely in colour, and in some species (most notably the
ornate and
Ocellated) there can be bold, bright patterns and eye-catching colours, often with spots and waving lines.
Uromastyx tend to range in colour from bright colours like green, blue, orange, and red through to more dull colours such as grey and brown. The larger members of the genus, such as the Egyptian and the Malinese, generally have the more plain colouration.
Seasonal variation
Like many reptiles, these uromastyx' colours change according to the temperature - during cool weather they appear dull and dark, but the colours become brighter in warm weather, especially when basking. The darker pigmentation allows their skin to soak up more sunlight.
