The only real way to get a true representation of the bait's colors and hi lite effects is to use a good light box with the camera tripod mounted. I don't have the room to bother building one just for a couple pictures once in a while. Optimally one could have a stationary camera at the light box so settings could remain based on the light conditions, which of course would be static.
Most cameras today have auto focus that can really mess with what you want shown. You'd have to set the camera to a manual mode and work the f-stop/shutter speed/set distance to get better renditions of the bait. My Canon program has an editing section where sharpness and contrast can be manipulated to some degree. The contrast is where I can dig up more of the hi lite effects in one color but I may or may not lose some color in any of the other colors.
Something else to consider is that most bait photos are taken with the bait laying on a surface. Just doing this stops a great deal of the light needed to show the hi lites. Try rigging the bait and getting your picture of it suspended in open air with a light background color, maybe hang a 2X3 foot piece of white cardboard on a door and offer light from both sides, top and bottom so shadows are eliminated. The backlighting and perimeter lighting a light box offers is absolutely the best but the white cardboard would be a somewhat-close second. To get the most out of a picture, light has to go thru the bait to get hi lite or pearl to really fire.
Background color will mess with what you want to show too with many colors. To get the best results for you, take several shots using different backgrounds colors. The denser the bait's color, the more agreeable the color will be to sitting on a contrast color of background. The more transparent a color is and the more hi lite effect you want to show, you'll want a back ground color that is similar to the bait's hi lite color with white being the best. In a lot of my pictures of blue or purple baits having hi lites of those colors I use a soft blue paper shop towel as the background to help kick start the hi lite with some positive contrast. White though is a solid background. A very light gray would work good too.
If you are using uv enhancer in your colors, expect some interference from it in your pictures. The enhancer is doing its job but it also confuses the camera if pictures are taken in shaded sunlight or on a cloudy day. I suggest making your picture bait, then adding the enhancer to the plastic and make your working baits.
Understand that indoor lighting and natural light are two entirely different worlds and pictures taken inside with artificial light will look substantially different in a picture taken in the sun or even shaded sunlight. A light box will get you your most consistent pictures.