Create a file with the following content.
Dracula//rgb(40,42,54)//rgb(248,248,242)//rgb(68,71,90)//rgb(98,114,164)//rgb(248,248,242)//rgb(41,50,55)//9//1//3//10//24//true//
Open ArcMenu settings -> Misc. -> Import Theme Preset, the file you just created.
Menu Theme -> Enable 'Override Menu Theme' -> Current Menu Theme Preset, select Dracula -> Apply