So I found an Essence, and when I went to generate my Sylesti, it ended up being a different color than I chose, and now it looks a bit weird >.<

In fact, all of the colors are much lighter than what I chose o.o;
Like when I chose pure red for its eyes(Don't judge x3), it changed it to a lighter pinkish-red.

Help on how to prevent this in the future? Also, is there any way an Admin can help me fix this...?

That's actually how the generator works. You won't always get the exact colors you put in and, in fact, are more likely to not get the precise colors you put in. There is a swing to the generator that will change the exact hexes by a few (or a lot) to produce a color somewhere within that spectrum you selected. When you generate, you're technically gambling, and you won't always get exactly what you wanted, but sometimes you will get lucky and get extremely close (if not dead on).

Generators are meant to have a "swing" on the color values of each color, throwing them off from the initial colors you picked by some points. It says on the generator page that colors won't be as accurate as with an enhanced essence as best.

So having some colors off from your initial choice is to be expected.

Edit: beaten xD

Oh okay. Dang.

Just be happy it stayed in the same color area. I have a Zebra that had red-purple stripes when I made it, then came out with poop-green stripes!

Similar thing here; I had an enhanced essence for qitari with slightly off white wings and the wings came out a sort of light mint green