Well, if I recall my leopards correctly, we're talking about a sandy-slightly yellow base with black spots -- not tiger orange, not lion-dun colored. Therefore, get a color wheel, locate the 'sandy-slightly yellow' color on it and go directly across from that ..in any shade/tone of light or dark depending upon your love of drama. It's pretty neutral, so you can pick almost anything, but directly across the color wheel will make the original color pop the most.

Espresso or deep red or purple are commonly used. Versace in fashion has used cyan and pale green as contrasts as well

I have a white creme leather sofa with a leopard pillow. I was looking for a pop of color to go with it and I chose a turquiosey shade throw and another pillow. Love it!