It looked palish brown/gold when I looked at it.
These Kaiju on Pacific Rim are actually hard to distinguish their true colors. You look at Otachi, and you think she's blue. Look at concept art and stuff, and she's grayish-blue with yellowish-white on the underside. You look at Mutavore and you think that he's grey. But when you look at it closely, you can't decide wether he's brown, yellow, or purple. Especially his glowing essence.
I looked at concept art and game stills for coloring
Actually, Mutavore is a hard case for me to color. I know he's gray in color. But if you look closely at concept art, pictures, and all that, you can notice that his claws, head, and she'll are some sort of yellowish brown color and his body is purplish blue. Then, as a second layer of color, he is given this grayish tone to avoid any resemblance to Hardship.
I noticed gray. I gave Mutavore a grayish blue based on this image: 31.media.tumblr.com/603928333a…
Look at its head and plates (back thingies). You'll see that the color changes. I made a foam figurine of Mutavore. Tried to make his skin look something other than blue. I succeeded in it. But I forgot to make its head grayish yellow. So now he has a yellow head