Here are where and what colour the guild marks are, also I am changing the guild mark colours for the Sabertooth members but not the place.

Nagisa - Side of her Neck - Blue at the top fading to Purple

Karma - Back of his Neck - Black fading to Red

Isogai - Right Upper Arm - Gold with a Sky Blue outline

Maehara - Left Upper Arm - Mint Green with a Golden Brown outline

Kayano - Left Side of her Forehead - Golden Orange with a Pale Orange outline

Rio - Her Right Ankle - Crystal Blue with a Sliver outline

Chiba - Back of Left Wrist - Pale Green with Golden Orange outline

Hayami - Back of Right Wrist- Dark green with Redish - Pink outline

Sting - Left Shoulder - Pale Blue with Pale Brown outline

Rogue - Left Shoulder - Pale Green with Pale Pink outline

Minerva - Left Waist - Gold with a Bright Red

Rufus - Middle of the Chest - Black Blue with Green outline

Orga - Right Waist - Indigo with a White outline

Yukino - Left Waist - Yellow with Blue outline

Shi - Between Shoulder Blades - Blue with Aqua Green outline

Ichi - Calf - Purple, Pink Speckles with a Mint Green outline 

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I made up Rufus's and Orga's place because I couldn't find it.