Commission: Adding Color to Line Art

I'm working on a fun project for a friend right now. She owns a hair salon and had asked an artist to draw a piece for her which would symbolize her business and her style. Here is the piece that was drawn for her (not by me):

Line art drawing of a hand, hair trimmer and flowers

My task is to add color to this piece to bring it to life. She's chosen a white, rococo style oval frame for the completed piece. Her only specific request was that it include the color red. I started by scanning the line drawing into Photoshop, duplicating the art layer, and removing the white background color. Then, the fun part - designing a color scheme and coloring the actual art. Here's the colorized version which features solid, saturated colors reminiscent of vintage art:

Line art drawing digitally colored in a vintage style

After tweaking the colors, I felt as if the design might appear a bit too flat, so I added some highlights and just a bit of shading. Here's the second version. Which do you prefer?

Line art with color, highlighting, and subtle shading

I'll share a photo of the final framed piece when it's complete. Let me know what you think of the colors I've chosen and which version of the art you prefer!