Color Palette:

1. Color Name: Red Velvet
   Hex Code: 
                            
                            #8B0000
                        
   Palette Description: This deep red color represents the seriousness and urgency of discussing sexually transmitted diseases. It grabs attention and conveys a sense of caution.

2. Color Name: Vibrant Orange
   Hex Code: 
                            
                            #FF6600
                        
   Palette Description: This bright orange color represents energy and enthusiasm. It adds a lively and engaging touch to the poster while symbolizing the importance of taking action and seeking information about sexually transmitted diseases.

3. Color Name: Pure White
   Hex Code: 
                            
                            #FFFFFF
                        
   Palette Description: This pure white color represents cleanliness and purity. It creates a clean and professional look for the poster, making the content easily readable and the information easily accessible.

4. Color Name: Deep Blue
   Hex Code: 
                            
                            #000080
                        
   Palette Description: This deep blue color represents trust and reliability. It adds a sense of authority and professionalism to the poster, encouraging viewers to trust the information provided about sexually transmitted diseases.

5. Color Name: Soft Gray
   Hex Code: 
                            
                            #808080
                        
   Palette Description: This soft gray color serves as a neutral background that complements the other colors in the palette. It helps balance the vibrancy of the other colors and creates a visually appealing contrast.

Note: It is important to consider the target audience, cultural sensitivities, and appropriate visual representation when designing a poster about sexually transmitted diseases.