It is probably a female, but you cannot rely completely on color in this species. I have seen small olive or brown males and juveniles of both species can be yellowish. I have even encountered a couple of very large females that were sufficiently green to convince me that they were males before I made a positive sex determination. To be sure of the sex, look at the external genetalia. In all stomatopods, the penises (gonopods) are located in the male as a pair of tubes hanging down from the inside base of the last walking leg. These are quite large and extend down 1/3 to 1/2 the length of the leg. The female gonopores are exposed through a plate on the ventral mid-line between the first pair of walking legs. I have posted images under the "sex pictures" thread in this Forum.
Roy